<template>
   <view>
    <!-- 使用自定义的搜索组件 -->
    <view class="search-box">
      <my-search @tap='searchChange'></my-search>
    </view>



      <view class="scroll-view-container">
         
      <!-- 左侧的滚动视图区域 -->
         <scroll-view class="left-scroll-view" scroll-y :style="{height: wh
+ 'px'}">
            <view :class="['left-scroll-view-item', active === i? 'active': '']" v-for="(item, i) in cateList" :key='i'
          @tap='cateChange(i)'>{{item.cat_name}}</view>
      </scroll-view>
         
      <!-- 右侧的滚动视图区域 -->
      <scroll-view class="right-scroll-view" scroll-y :style="{height: wh +
      'px'}" :scroll-top="scrollTop">
         <view class="cate-lv2" v-for="(item2, i2) in cateLevel2" :key="i2">
            <view class="cate-lv2-title">/ {{item2.cat_name}} /</view>
            
          <!-- 动态渲染三级分类的列表数据 -->
            <view class="cate-lv3-list">
               
            <!-- 三级分类 Item 项 -->
               <view class="cate-lv3-item" v-for="(item3, i3) in item2.children" :key="i3" @tap='toGoodsList(item3)'>
                  
              <!-- 图片 -->
                  <image :src="item3.cat_icon"></image>
                  
              <!-- 文本 -->
                  <text>{{item3.cat_name}}</text>
                 
            </view>
              
          </view>
           
        </view>
      </scroll-view>
        
    </view>
     
  </view>
</template>

<script>
  export default {
    data() {
      return {
        // 窗口的可用高度 = 屏幕高度 - navigationBar高度 - tabBar 高度
        wh: 0,
        cateList: [],
        active: 0,
        // 二级分类列表
        cateLevel2: [],
        scrollTop: 0
      };
    },
    onLoad() {
      // 获取当前系统的信息
      const sysInfo = uni.getSystemInfoSync()
      // 为 wh 窗口可用高度动态赋值
      this.wh = sysInfo.windowHeight - 50
      this.getCateList()
    },
    methods: {
      async getCateList() {
        const res = await this.$http.request('/api/public/v1/categories', '', 'get')
        this.cateList = res.message
        this.cateLevel2 = res.message[0].children
      },

      cateChange(i) {
        this.active = i
        this.cateLevel2 = this.cateList[i].children
        this.scrollTop = this.scrollTop ? 0 : 1
      },
      toGoodsList(item) {
        uni.navigateTo({
          url: '/subpkg/goods_list/goods_list?cid=' + item.cat_id
        })
      },
      searchChange() {
        uni.navigateTo({
          url: '/subpkg/search/search'
        })
      }
    }
  }
</script>

<style lang="scss" scoped>
  .search-box {
    // 设置定位效果为“吸顶”
    position: sticky;
    // 吸顶的“位置”
    top: 0;
    // 提高层级，防止被轮播图覆盖
    z-index: 999;
  }

  .scroll-view-container {
    display: flex;

    .left-scroll-view {
      width: 120px;

      .left-scroll-view-item {
        line-height: 60px;
        background-color: #f7f7f7;
        text-align: center;
        font-size: 12px;

        // 激活项的样式
        &.active {
          background-color: #ffffff;
          position: relative;

          // 渲染激活项左侧的红色指示边线
          &::before {
            content: ' ';
            display: block;
            width: 3px;
            height: 30px;
            background-color: #c00000;
            position: absolute;
            left: 0;
            top: 50%;
            transform: translateY(-50%);
          }
        }
      }
    }
  }

  .cate-lv2-title {
    font-size: 12px;
    font-weight: bold;
    text-align: center;
    padding: 15px 0;
  }

  .cate-lv3-list {
    display: flex;
    flex-wrap: wrap;

    .cate-lv3-item {
      width: 33.33%;
      margin-bottom: 10px;
      display: flex;
      flex-direction: column;
      align-items: center;

      image {
        width: 60px;
        height: 60px;
      }

      text {
        font-size: 12px;
      }
    }
  }
</style>
